Bladena helps prevent cracks in blades

DENMARK: Blade research company Bladena has developed a device to reduce cracks occurring in blades.

Bladena’s CTO, Find Jensen, demonstrates the company's d-string

The product aims to alleviate stress on the adhesive glue in its trailing edge caused when a turbine's rotor rotates. This can lead to cracks.

The company’s D-String is made of nylon, with conic connectors attached to the blade. It is installed in-between two trailing edge panels of a blade to prevent it bending or 'pumping' when it rotates. Measurement devices ensure the correct tension in the string.

Bladena’s CTO, Find Jensen, who founded the company in 2011, has been working closely with blade repair company Total Wind Blades (TWB).

Jensen said: "Glue binds the blades together and at the edge it’s a weak point and when they rotate they bend, or as well call it 'pump'. We worked to minimise this ‘pumping’ action."

The company’s D-String is currently being tested in a Danish manufacturer's turbine, owned by Vattenfall, in Denmark after it was installed one year ago. TWB measured the ‘pumping deformation’.

Jensen said: "The pumping was measured and then the D-String was fitted. TWB found the pumping deformation was reduced by 95%. This can extend the lifetime in the binding by many years."

The D-String was also installed on a US manufacturer's turbine in America a few months ago. Bladena was unable to release the names of the wind turbine companies.

Funding for the project came from the Danish government’s Energy Development Demonstration Programme and the D-String has become a patented technology.